Coated metallic article.



lW. C. ROBINSON.

COATED METALLIC ARTICLE. APPLIUATION FILED 23.15. 190g.

Patented Mains,

WITNESSESI A Amal; A PAWS@ caused to penetrate the UmTEnS wiLLiAM c. aonruson, or rrrrsnmaa,A rnNNsrnvAma.

con'rnn 'METALLIC narrow.

Spcincation of Letters Patent. i Patented Mar.,

d, 191ML.

Application med `April 15, 1909.l Serial No. alhll.

To all whom 'it may concern:

lie it known-thatl, WILLIAM C. y@RoninsoN, residing at Pittsburg, in the county of Allegheny and State of Pennsylvania, a citizen of the lUnited States, 'have invented or.

discovered a certain new and useful {lmprovement -in Coated Metallic Articles, vof which improvement the following is a speciication.

lin the practice of m invention the meta-l-4 lic article to .bev coat treatment, y whereby a ing is caused not only face of the article', greater or less metallic skin or coatextent into the surface.4 A skin or coating thus formed diers' from a metallic coating which is deposited electrically upon the surface of the article, or which' is formedd thereon by dipping the article jinto a molten bath, in that in eitherfof the-latter cases the coating may l OH; whereas when the -coating materialis surface, it is' racticallyimpossible to se arate it there rom, and even if it be filed surface, the metal of the article willstlll be found to be substantially-covered by the coating metal.. This metallic coating can best be -applied by the method known as sherardizing, substantially as described in Letters Patents of the United States No. 701,298 and No. 829,386. The invention is. not however limited to any 'specific method of ap lying such penetrative metallic coating.. either is the invention limited to any particular metal which may be employed for the penetrative metallic coating. ll pre# fer however to employ zinc for that purpose, particularly in coating articles of iron or steel. A zinc coating applied in the manner above stated cannot be destroyed or"chipped off in ordinary handling, or by ordinary abrasion, since it penetrates into the surface of the article, and seems to coat its individual molecules or particles. y

While zinc and other metals afford a highly ecient protection against the destructive action of alkalies, they are injuriously affected to a greater or less de ree by contact with acids. Therefore l appy to the metallic4 coating above described, a second coating of an acid-resisting substance, which is also of such character and applied in such manner as to notonly form a coating, but also to penetrate to a material extentthe initial metallic coating and the article itself.

.coating may be dipped `aninay be dissolved Ais nrst subjected to a' to adhere to the sur- 'butto penetrateto -ak be knockedor chipped.

`ively resist the indivi own to the original' metallic articlean initial For this second coating li preferably employ a waxy Substance, and while other waxes, both 'vegetable and mineral, are .adapted for this purpose, I prefer to use paraiiin. The parau may be merely melted and. heated to a high temperature, and the article having the initial `metallic therein; or the parin a volatile liquid carrier, such as gasole'ne, and thus applied to 'the article, when the gasolene, having performed its function as a carrier, will evaporate, leaving the paraffin in position. lin either operation a thin skin or coating of wax will be applied to the article, and the wax coating is thus also caused to penetrate the metallic coating and the article itself. When this wax coatin has dried, it has been found that even iig it be scraped away asclosely to the metal as possible, there will still remain a sufficient quantity to eiectaction of acids, the wax apto have formed a coating around the ual molecules or particles of metal, and to have penetrated pores in the metallic face of the article.

Daarin coatingand in the sur- By thus applying to a penetrating metallic coating resistant to alkalies, and a second penetrating coating resistant to acids, there is obtained a resultant composite or mechanically combined coating, which has also penetrated and mechanically combined with the metal of the surface of the article betected against the action of either alkalies or acids by a coating which cannot be broken orstripped away by ordinary handling. or abrasion. The second coating, when made of wax, may be so thin as to be suciently transparent to disclose the character of the underlying metal surface, and at the same time adord an efficient acidproof coating.

The invention is adapted to the coating of any metallic article which is subject to injury by alkalies and acids. It has been found of great Value for the protection of iron and steel conduits for electrical conductors, and l.fittings used in connection therewith. These conduits must often be placed in the walls of buildings and other structur positions slag from made of cement or concrete` comcontainlng metallic cmder and smelting furnaces. This clnder and filled vall thev `neath, so that the individual molecules or jp'articles of sald surface are effectively prois very hard, and usually contains acids Which are highly injurious to iron and steel. It is found that conduits coated as herein described are particularly serviceable in such situations; the coating is not injured b abrasion of such substances, and it eiii- `c1ently protects the body ofthe conduit from pitting and corrosion.

The accompanyin drawing illustrates as well as it can be i lustrated, a section of pipe 1, coated in accordance with the invention, the zinc and ara'in penetrating the surface of the article being indicated by the small dots.

4I claim as my invention:

1. A metallic article havino a metallic coating or skin adherent to and penetrating the surface of the article, and a second coating differing in character from the first and adherent to and penetrating said irst coatlng.

f l A metallic article having a coating or skin of zinc adherent to and penetratin the surfaceof the article, and a coating o paraiin adherent to and pentrating the zinc coating. n

3. A metallic article having a metallic coating adherent to and enetrating the surface of the article, and) a trans arent acid-resistant coating adherent to an penetrat-ing said metallic coating.

4. Metallic tubing havingacoating of zinc adherent to and penetrating the surface of the tubing anda coating of arain. adherent to and. penetrating the zinc coating.

In testimony whereof, I hafe'hereunto sct my hand.

. WILLIAM C. ROBINSON.

Witnesses CHARLES BAnNE'r'r, FRIEDA E. WOLFF. 

